Date: 9th October 2024
1. What is Venous Congestion?
Venous congestion is a pathological state where elevated right sided venous pressures reduce organ perfusion. Unlike volume overload, which refers to excessive fluid in tissues, venous congestion is characterized by increased venous pressure that obstructs the drainage of blood from organs, particularly those that are encapsulated, like the kidneys. This high pressure reduces the perfusion gradient across organs, impairing oxygen delivery leading to organ injury. Encapsulated organs are especially prone to damage because their limited ability to swell exacerbates the harmful effects of congestion. This process can lead to acute kidney injury (AKI), an increased need for dialysis, and is associated with increased mortality.(1, 2)
2. How to Detect Venous Congestion
Traditional markers like central venous pressure (CVP) are frequently used to approximate venous congestion, but their accuracy is limited. CVP reflects pressure at the right atrium, which doesn't always correlate with venous pressures at the organ level, particularly in the kidneys. Variability in intra-abdominal pressure and the compliance of the venous system mean that for any individual patient, an elevated CVP does not accurately detect organ level congestion.
Instead, attention has shifted towards Doppler ultrasound of key vessels to assess venous congestion at the organ level. Doppler evaluations of the hepatic vein, portal vein, inferior vena cava (IVC), and intra-renal veins provide more direct insights into venous pressure. These measurements form the basis of the VeXUS score, a tool designed to quantify venous congestion.(1)
3. The VeXUS Score
The VeXUS score was developed to quantify venous congestion by integrating Doppler assessments from multiple veins. It examines flow patterns in the hepatic vein, portal vein, IVC, and intra-renal veins to determine the severity of congestion. A score of 0 or 1 typically indicates no congestion, whereas scores of 2 or 3 represent significant congestion. A higher VeXUS score is associated with an increased risk of organ dysfunction, particularly AKI. This scoring system helps clinicians diagnose, trend, and assess response to decongestive therapies.
4. Causes of Venous Congestion
Venous congestion is often mistaken for volume overload, but they are distinct. Volume overload refers to excessive fluid in tissues, while congestion is characterized by high pressures in the venous system, which can occur even without significant fluid accumulation. Congestion can be caused by a variety of factors beyond fluid administration, including right ventricular (RV) failure, left ventricular failure, pulmonary hypertension, tricuspid regurgitation, and pericardial effusions. In these cases, increased venous pressures lead to impaired venous return and subsequent organ dysfunction, even if the overall fluid balance is not positive. Importantly, this also means that the treatment for venous congestion is not simply diuresis, but rather, diagnosis and treatment of the underlying cause.
5. Limitations of the VeXUS Score
Although the VeXUS score is a valuable tool for assessing venous congestion, it has some limitations. It was initially developed and validated in cardiac surgery patients, where the pathophysiology may differ from other critically ill populations, such as those with septic shock.(2, 3) The thresholds for congestion identified in cardiac surgery patients may not directly apply to other clinical scenarios, meaning clinicians need to adapt their interpretation based on the underlying cause of congestion. Additionally, it can be tempting to treat all congestion with diuretics. Although in some cases this is appropriate, the most important step before this is determining the cause of congestion. Pericardial tamponade can cause congestion, which you do not want to diurese!
6. The Future of Congestion Management
The future of venous congestion management lies in disease-specific approaches. Not all forms of congestion are equal, and treatment should be tailored to the underlying cause. For example, RV failure-induced congestion may require a different management strategy than congestion caused by fluid overload. Additionally, the integration of novel tools like the VeXUS score into bedside assessments allows for more targeted therapies, such as the use of diuretics or inotropes, to alleviate congestion without causing harm. Future research will focus on refining these tools, determining more precise thresholds for intervention, and understanding the best treatment approaches for different types of venous congestion.
About the writer
Dr Ross Prager, an intensivist in Canada interested in hemodynamics, critical care ultrasound, and helping researchers be more productive and impactful. He is working on a tool Resub that automates manuscript reformatting for researchers, helping prevent the waste of time, effort, and money spent formatting manuscripts.
Follow Ross on Twitter/X for more top notch PoCUS educational content https://x.com/ross_prager
References
1. Beaubien-Souligny W, Rola P, Haycock K, Bouchard J, Lamarche Y, Spiegel R, et al. Quantifying systemic congestion with Point-Of-Care ultrasound: development of the venous excess ultrasound grading system. Ultrasound J. 2020;12(1):16.
2. Prager R, Arntfield R, Wong MYS, Ball I, Lewis K, Rochwerg B, et al. Venous congestion in septic shock quantified with point-of-care ultrasound: a pilot prospective multicentre cohort study. Can J Anaesth. 2024;71(5):640-9.
3. Prager R, Argaiz E, Pratte M, Rola P, Arntfield R, Beaubien-Souligny W, et al. Doppler identified venous congestion in septic shock: protocol for an international, multi-centre prospective cohort study (Andromeda-VEXUS). BMJ Open. 2023;13(7):e074843.
Do you want to learn echocardiography and how to apply this skill clinically?
Check out our upcoming courses below ⬇️
Comments